Thursday, March 15, 2012

Payback‘s A Bitch: Neurotoxin BMAA In Shark Fins

We kill 100 million sharks a year to accommodate Asia's insatiable obsession for shark fins, and now the Elasmobranch is fighting back. Payback's a bitch ain't it?

Shark fins are just tasteless cartilage with fibrous protein collagen. Chinese believe that shark fins can boost sexual potency, enhance skin quality, and even prevent heart disease. But the benefits of shark fins have never been significantly proven, nor has shark cartilage been reviewed by the U.S Food and Drug Administration (FDA). Entrepreneurs in Taiwan even substitute shark fins with Tilapia fins due to their bland similarities. But this hasn't stopped the massacre, yet.

Image: chinadecoded.com

A group of scientists from the University of Miami recently discovered that shark fins contain high level of cyanobacterial neurotoxin β-N-methylamino-L-alanine (BMAA). BMAA is linked to a plethora of neurodegenerative brain diseases such as Alzheimer's disease and Amyothrophic Lateral Sclerosis (ALS).
The group targeted seven shark species around South Florida for the experiment. The sharks were temporarily caught and brought alongside the vessel for non-lethal tissue collection, whereby a 2 X 2 cm clip was removed from the trailing edge of the first dorsal fin, and a 4mm muscle biopsy sampled from the hepaxial muscle on the shark's left flank. All captured animals were later released. A few Great Hammerhead Sharks samples, however, were obtained as a result of recreational fishing activities.

Blacktip sharks are often caught by beach anglers. Image: outdoor.com

The results showed high level of BMAA detected in all seven species of sharks sampled. But among the same species the results weren't consistent as some fins exhibited the presence of BMAA while some didn't. The researchers also detected BMAA in fins of sharks collected in areas that had no active cyanobacteria bloom. This could be attributed to the migratory habit of sharks. The researchers reasoned that the cyanobaterial toxin ended in the apex predator as they consumed toxin-accumulating crustaceans and fish. The tissue sample collected from the Great Hammerhead showed that BMAA was also present in other vital organs such as kidney and liver.

The author, however, mentioned that the study did not include sharks outside of South Florida, and hence it didn't demonstrate the widespread BMAA detection in sharks. But sharks are migratory animals, so a toxin-carrying animal might still end up in your bowl someday.

Is this a good news?
Definitely not for shark fin soup lovers, but it's a good news for me and the sharks.